Elastic fin erector



Dec. 17, 1963 sw M I 3,114,287

ELASTIC FIN ERECTOR led Sept; 22, 1961 2 Sheets-Sheet 1 Dec. 17, 1963 F. H. SWAIM ELASTIC FIN ERECTOR FRANK H. SWAIM INVENTOR ATTORNEYS 2 Sheets-Sheet 2 W0 BY I 1 am Filed Sept. 22, 1961 3,114,287 ELASTIC FIN ERECTOR Frank H. Swaim, Silver Spring, Md, assignor to the United States of America as represented by the Secretary of the Navy Filed Sept. 22, 1961, Ser. No. 140,151 3 Claims. (Cl. 89-1.7)

This invention relates to an aerial missile fin erector; more particularly, it relates to an elastic fin erector.

Aerial missiles that are stored in small compartments, such as shipboard magazines, are commonly provided with folding fins to save space. When such a missile is mounted on a launcher, the fins are automatically erected by suitable means on the launcher structure. Such means have usually included cam type actuators, which are particularly vulnerable to damage by rocket motor blast. Moreover, if the missile is not fired for some reason, because it was loaded during a practice run or an alert, for example, it is necessary to re-fold the fins before the missile is returned to its magazine compartment.

To simplify this loading and unloading procedure, the present invention contemplates an elastic band attached to each pair of fins, and a clip for holding the fins in their folded position. As the missile is fired from the launcher, the clip is moved out of contact with the fins to permit the band to erect them. Should the missile not be fired, however, the clip is not moved and the fins will remain folded.

It is therefore an object of the present invention to provide a simpie, reliable fin erector which may be used with existing missiles and missile handling equipment.

Another object of the invention is to provide a fin erector which is not operable until the missile is launched.

A further object of the invention is to provide a fin erector which is light in weight and which does not create a safety hazard.

Other objects and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective view of elastic bands of the present invention attached to the erected fins of a missile;

FIG. 2 is a view similar to FIG. 1, but showing the fins in folded position;

FIG. 3 is a plan view of the elastic band of the present invention;

FIG. 4 is a section on line 4-4 of FIG. 3; and

FIG. 5 is an enlarged perspective view of a fin holding clip mounted on a missile, with the missile fins omitted for clarity.

Referring to FIGS. 1 and 2, a missile of the type utilizing folding fins is indicated at 10. Equally spaced about the circumference of the aft end of the missile are four fins 12, each comprising a movable portion 14 pivotally mounted on the hub 16 of a stationary base portion 18. The fins are designed to fold into overlapping relationship, as shown in FIG. 2, and are arranged to form two pairs. The movable portions 14 of the lower pair in FIG. 2 pivot in opposite directions and lie against the missile body in folded position. The movable portions 14 of the upper pair also pivot in opposite directions but overlie the movable portions of the first pair of fins.

Attached to the missile body midway between the adjacent fins of the upper and lower pairs are bolts 20, the heads of which are spaced from the body. Mounted on the missile by the bolts 20 are clips 22 for holding the fins 12 in their folded position against the erecting force exerted by elastic bands 24 attached to each pair of fins. Each elastic band 24 is shorter than the distance between the ends of each pair of fins so that it exerts a relatively 3,114,287 Patented Dec. 17, 1963 small force on the fins when they are erected, but a relatively strong erecting force when they are in folded position.

Referring to FIGS. 3 and 4, which illustrate the elastic band 24 in greater detail, it is seen that a pocket 26 is formed on each end of the band to receive the end tip of a fin. Each pocket consists of a non-elastic strap 28, of nylon for example, the ends of which are embedded in the elastic band 24 so that they are integral therewith. The strap 28 is folded at two points 30 and 32 so that the folds form an angle equal to the angle formed by the converging side edges of the end tip of a fin 12. The length of strap extending between the folds 30 and 32 is at right angles to the band 24 and forms with the folds a receptacle conforming to the outline of a fin tip.

The Width of the band 24 is equal to the width of the hubs 16 so that when the fins 12 are folded the band will be stretched over the hubs but will not extend over the hub corners. This eliminates the points of high stress and the cutting action that the hub corners would otherwise cause.

In order to use a relatively narrow band while providing a cross-sectional area great enough to withstand the necessary elongation, the band is provided with a crosssection having a relatively thick central portion and a curved outer surface.

Referring now to FIG. 5, the clip 22 is shown mounted on the missile by a pair of spaced legs 34 straddling the bolt 20 between the bolt head and the missile. The clip is further comprised of a wall 36 extending from one end of the legs 34 at right angles thereto, and of two spaced arms 38 and 46 extending from the wall parallel to the legs. The upper arm 38 is shorter than the arm 40 to allow the upper pair of fins to be released before the lower pair. The legs 34 are longer than the arm 40 to insure that the clip will remain mounted on the missile until the lower pair of fins has been released. To remove the clip from the missile as the latter is launched, an abutment bar 42 is attached to the launcher structure (not shown) and engages the wall 36 above the upper arm 38 as the missile begins to move.

In use, elastic bands 24 are attached to the tips of the upper and lower pairs of fins, as shown in FIG. 1. The fins are then folded to the position shown in FIG. 2 and a clip 22 is mounted on the missile at each bolt 20 by sliding the legs 34 beneath the bolt head. The arms 38 and 41 are spaced to readily receive the aft edges of the movable fin portions 14 of the upper pair of fins, while the space between the legs 34- and the arm 41' is sufficient to receive the edges of the movable portions of the lower pair of fins. It is in this condition that the missiles are stored.

If a missile is loaded on the launcher but is not fired, it may be returned into the storage area immediately, since its fins would have remained folded. If the missile is fired, however, the abutment bar 42 will prevent the clip 22 from moving with the missile and thus permit the elastic bands 24 to erect the folded fins in their proper sequence. This erecting movement of the fins takes place with great rapidity, and the sudden halt when fully erected tends to jar the band free. In addition, the forces produced by the remaining tension in the band and the flow of air thereagainst combine to cause the bands to be released from the fins and fall free of the missile.

A strong wind blowing against the erecting movement of the fins will strike the central portion of the band and create additional tension therein to combat the adverse effect of the wind.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It should therefore be understood that within 1. In combination with a missile launcher and an aerial missile carried thereby, said missile having pairs of oppositely folded fins, a fin erector', comprising means removably mounted on said missile for normally holding said fins in folded position, means on said missile launcher and engageable with said holding means for causing said holding means to become inoperative upon launching of the missile, an elastic band associated witheach pair of fins, and non-elastic means on each end of said band and initially engaged with the free end portions of the fins, said band initially extending over portions of the exterior surfaces of said pair of fins and urging the fins toward erected positions, the launching of said missile causing said second-mentioned means to remove said holding means,

thereby allowing said elastic bands to erect said pairs of oppositely folded fins, and movement of said fins to erected positions relieving tension on said bands, whereby said bands and the non-elastic means thereon will be displaced from the missile by airflow during the initial stage of missile flight.

' 2. The combination according to claim 1, wherein said non-elastic means comprises a non-elastic strap embedded in said band and folded to conform to the shape of and to receive the end of a fin.

3. The combination according to claim 1, wherein said elastic band is solid and has an unstretched length which is less than the distance between the extremities of a pair of said fins.

References Cited in the file of this patent UNITED STATES PATENTS Dobrikin July 11, 1961 

1. IN COMBINATION WITH A MISSILE LAUNCHER AND AN AERIAL MISSILE CARRIED THEREBY, SAID MISSILE HAVING PAIRS OF OPPOSITELY FOLDED FINS, A FIN ERECTOR, COMPRISING MEANS REMOVABLY MOUNTED ON SAID MISSILE FOR NORMALLY HOLDING SAID FINS IN FOLDED POSITION, MEANS ON SAID MISSILE LAUNCHER AND ENGAGEABLE WITH SAID HOLDING MEANS FOR CAUSING SAID HOLDING MEANS TO BECOME INOPERATIVE UPON LAUNCHING OF THE MISSILE, AN ELASTIC BAND ASSOCIATED WITH EACH PAIR OF FINS, AND NON-ELASTIC MEANS ON EACH END OF SAID BAND AND INITIALLY ENGAGED WITH THE FREE END PORTIONS OF THE FINS, SAID BAND INITIALLY EXTENDING OVER PORTIONS OF THE EXTERIOR SURFACES OF SAID PAIR OF FINS AND URGING THE FINS TOWARD ERECTED POSITIONS, THE LAUNCHING OF SAID MISSILE CAUSING SAID SECOND-MENTIONED MEANS TO REMOVE SAID HOLDING MEANS, THEREBY ALLOWING SAID ELASTIC BANDS TO ERECT SAID PAIRS OF OPPOSITELY FOLDED FINS, AND MOVEMENT OF SAID FINS TO ERECTED POSITIONS RELIEVING TENSION ON SAID BANDS, WHEREBY SAID BANDS AND THE NON-ELASTIC MEANS THEREON WILL BE DISPLACED FROM THE MISSILE BY AIRFLOW DURING THE INITIAL STAGE OF MISSILE FLIGHT. 